1. Field
The present disclosure relates to an apparatus for initially driving a sensorless BLDC motor, and a method using the same.
2. Background
BLDC motor (also brushless DC motor) is a device used in various fields including information processing devices such as a floppy disk drive as well as home appliances such as a refrigerator, an air conditioner or the like. An additional detector is provided to detect the rotational speed of a BLDC motor, the position of a rotor, and the like. However, a BLDC motor provided with no detector is referred to as a sensorless BLDC motor.
In general, the step of driving a motor can be divided into three sections, such as an initial position setting section, an open loop section and a closed loop section. The initial position setting section is a section in which the rotor starts to rotate from a stopped state to move the rotor to a predetermined position, and the open loop section is a low-speed section in which a back electromotive force is not sensed subsequent to setting up the initial position of the rotor, and the closed loop section is a section in which the sensing of a back electromotive force is enabled to normally control the rotor.
According to a typical 180 degree conduction mode, in order to drive a BLDC motor, a predetermined size of current is initially applied to a U-phase for a predetermined period of time to align the rotor of the BLDC motor to the U-phase and then the BLDC motor is immediately driven through sensorless control. In other words, in a state that the rotor of the BLDC motor is aligned to the U-shape, it is assumed that the position of the rotor is zero, and the speed of the motor is immediately controlled through the position of the rotor through sensorless control using this position as a reference position.
In case of controlling the speed of a BLDC motor in this manner, alignment is not completely carried out when the motor is in a high load state during the initial alignment or the position of the motor rotor is not aligned to a reference position but positioned adjacent to the reference position. When the motor is controlled using a sensorless algorithm in such an incomplete initial alignment state of the motor rotor, it may cause a problem in which the driving of the motor is failed due to an initial position error of the motor rotor.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.